1. Field of the Invention
The present invention generally relates to Power-over-Ethernet (PoE) systems. More specifically, the present invention relates to analysis of PoE devices (or Powered Devices (PD)) in a PoE system.
2. Related Art
In conventional PoE systems, a power sourcing equipment (PSE) chip analyzes characteristics of a PD and can control the supply of power to the PD. This analysis and control by a PSE chip occurs through an Ethernet interface including a PSE physical layer (PHY) chip and a PD PHY chip with a data link in between. In this system, the PSE PHY chip typically handles physical layer 1 functions and drives the link, activity, speed, and PoE light-emitting diodes (LEDs). This system is inefficient in that, with the PSE chip separate from the PHY, a host CPU needs to collect information from the PSE chip and send it to the PSE PHY chip in order for PoE status to be displayed. In some systems, the PSE chip drives the LED independently of the PHY chip, which is expensive. In addition, smaller and less expensive PoE systems that are more efficient than conventional PoE systems are currently desired in the industry. Therefore, what is needed is a smaller, more efficient PD analysis and power control system that saves host CPU processing time and power, and eliminates the need for additional communication interfaces. As exemplified by conventional cable diagnostics, certain system attributes can be determined in a PoE system through signal analysis, and this signal analysis can be done in a PHY chip. It would be useful to build upon the concept of conventional cable diagnostics to realize a PoE system that addresses the deficiencies of conventional systems and meets the aforementioned goals.